This invention relates to tetramethylene oxide (TMO) compounds which exhibit superior clay and oily soil removal even in very low-built detergent systems. More particularly, this invention encompasses zwitterionic compounds characterized by a particular placement and number of TMO groups and particular hydrophobic groups. Importantly, the TMO moiety can be introduced into the instant compounds using tetrahydrofuran as a precursor. Tetrahydrofuran, in turn, is available from plant by-products such as corncobs, oat hulls, cottonseed hulls, and bagasse. To this extent, the instant compounds are not based on scarce petrochemical feedstocks in the manner of ethylene oxide-containing detersive surfactants.
Zwitterionic compounds, i.e., the so-called "internally neutralized" surface active compounds having both positive and negative charge centers, are known. In contrast with many prior art zwitterionics, the instant invention encompasses zwitterionic compounds having a substituent which provides both charge separation and hydration interposed between the oppositely-charged centers of the molecule.
Various zwitterionic compounds are known, and attempts have been made to tailor these compounds to provide detersive surfactants.
U.S. Pat. No. 3,684,427, to Walz, et al., issued Aug. 15, 1972, discloses alkoxylated zwitterionic surfactants and their use in fabric dyeing operations.
Belgian Pat. No. 813,502, to GAF Corporation, relates to di-ethoxylated quaternary ammonium compounds, phosphated or sulfated to form amphoteric surfactants. The compounds contain two alkylene oxide chains. U.S. Pat. No. 3,505,396, to H. L. Sanders, et al., issued Apr. 7, 1970, relates to sulfopropylated amphoteric surfactants containing ethylene oxide chains. U.S. Pat. No. 3,673,158, to A. M. Reader, et al., issued June 27, 1972, relates to sulfobetaine glycol modified with poly(ethylene terephthalate). U.S. Pat. No. 3,239,560, to C. M. Cambre, et al., issued Mar. 8, 1966, relates to the preparation of sulfobetaines having a hydroxy-substituted alkylene moiety interposed between the positive and negative charge centers of the surfactant-type molecules. U.S. Pat. No. 2,185,163, to H. Ulrich, issued Dec. 26, 1939, relates to alkoxylated derivatives of amine oxides containing anionic substituents. U.S. Pat. No. 2,115,250, to H. A. Bruson, issued Apr. 26, 1938, relates to alkoxylated amines and their salts and to the quanternary ammonium bases and salts derived from said amines. British Patent Specification No. 465,200, complete specification accepted April 26, 1937, relates to quaternary ammonium or phosphonium, or tertiary sulfonium, compounds containing ether or polyether groups.
The co-pending application of Laughlin, Gosselink, Cilley, and Heuring, Ser. No. 493,951, filed Aug. 1, 1974, now abandoned, relates to zwitterionic surfactants having ethylene oxide moieties interposed between the cationic and anionic charge centers. The co-pending application of Laughlin, Gosselink, and Cilley, Ser. No. 493,956, filed Aug. 1,1974, now abandoned, relates to di-ethoxylated zwitterionic compounds having ethylene oxide groups interposed between the charge centers.
U.S. Pat. Nos. 3,668,240, issued June 5, 1972 and 3,764,568, issued Oct. 9, 1973, both to Barbera, disclose zwitterionic detergents having a 1,4-(2-butenylene) moiety between charge centers. U.S. Pat. Nos. 3,452,066, issued June 24, 1969, and 2,781,390, issued Feb. 12, 1957, both to Mannheimer, broadly relate to various zwitterionic surfactants optionally containing a seemingly limitless variety of oxygen-containing, presumably hydrophilic, moieties, including alkylene oxides. U.S. Pat. No. 3,769,311, issued Oct. 30, 1973, to Armstrong and Dawald, discloses ethoxylated ammonio carboxylate zwitterionics, and describes compounds having limited ranges of ethyleneoxy and hydrophobic groups attached to the positive charge center. Also, Belgium Arrete No. 806,567 issued Oct. 29, 1973 to Recket and Colman Products, Ltd., discloses anionic ethoxylated amino sulfonates. (See also Japanese 3555 (1962), to Komori and Kashiwabara, Chem Abstracts 53:4756e; British Pat. No. 1,296,351, complete Specification published Nov. 15, 1972, to Cheng et al.; U.S. Pat. No. 3,178,366, issued Apr. 13, 1965 to Du Brow and Brandiff; U.S. Pat. No. 2,940,816, issued June 14, 1960 to Sniegowski; and German Application No. 1,159,957, filed Nov. 8, 1960 by Glabisch, et al., for other zwitterionic and/or quaternary ammonium compounds.)
While a variety of surfactant classes are known, i.e., nonionic, anionic, cationic and zwitterionic, few of the usual types of detersive surfactants provide the advantageous performance of the instant compounds. The shortcomings of the art-recognized surfactants are well-known, and such materials must be built and/or otherwise precisely formulated to provide good soil removal under a variety of conditions. Moreover, it is common practice to blend various types of surfactants with builders to achieve both particulate and oily soil removal, since few, if any, surfactants are highly effective for removing both types of soil. Remarkably, the compounds herein exhibit detergency performance which approaches or exceeds many fully formulated and built detergent compositions in present commercial use, even without the use of builders, surfactant blends, or additives.
The instant invention is based on the discovery that the TMO moiety, properly interposed between the charge centers of zwitterionic surfactants having particular hydrophobic groups, provides compounds which exhibit unexpectedly high particulate soil removal performance in unbuilt laundry baths. Moreover, the compounds of this type are effective for removing oily soil.
The importance of the present invention is readily seen. A variety of surfactant types are known to remove soils, but none effectively remove both oily an particulate soil. Moreover, commercial detergent compositions are usually formulated with inorganic builders to remove a variety of soils under a variety of conditions. While such compositions are effective, the use of high concentrations of inorganic builders has raised questions regarding their presence in improperly treated sewage effluents. While organic builders are effective, they are expensive, especially when considering the substantial amounts used in common laundry situations.
The importance of the present invention is further seen when considering that other zwitterionic compounds having smaller, less extensively hydratable moieties (e.g., 2-hydroxy-1,3-propylene) separating the charge centers require builders and/or electrolytes to provide solubility and good cool water detergency (see, for example, U.S. Pat. No. 3,619,115, issued Nov. 9, 1971, to Diehl and Smith). The high water solubility of the preferred compounds herein eliminates the need for solubilizing additives such as builders or other electrolytes.
Finally, as noted above, the TMO-based compounds herein are prepared using tetrahydrofuran, rather than ethylene oxide, as a primary feedstock. The current and projected cost and availability of petrochemicals makes this an important consideration to detergent manufacturers. It is to be recognized that the zwitterionic surfactants herein are excellent emulsifiers and suspending agents, and are useful in a variety of compositions other than for their detergency function. For example, the compounds herein are useful spreading aids for use with herbicides and insecticides. The compounds are also useful as oil recovery aids, ore flotation aids, and the like.
It is an object of the present invention to provide zwitterionic detergent compounds which remove both particulate and oily soil from flexible substrates such as fabrics, as well as from hard surfaces such as walls and floors.
It is another object herein to provide zwitterionic compounds which can be used to cleanse both fabrics and hard surfaces without the need for builders or additives.
It is another object to prepare detersive surfactants using tetrahydrofuran as a feedstock.
These and other objects are obtained herein as will be seen from the following disclosures.